Retractable thrusters are known for marine applications. Conventional retractable thrusters either drop-down vertically or pivot downwards around a hinge. Vertically retractable units have one set of hydraulic rams for lifting/lowering the thrusters and another mechanism for turning the thrusters to their desired orientation. The turning mechanism can be one or more hydraulic rams operating via a lever system to give rotary motion over a limited angle, or a geared motor (electric or hydraulic) acting on a large diameter steering gear via small diameter pinions (either singly or in groups spaced around the steering gear wheel). Such arrangements are complex and require both axial and rotary actuators with their concomitant control systems, cabling and hull penetrations.